# probability
## English

Wikibooks

### Etymology

From Middle French probabilité, from Latin probābilitās (“probability, credibility”), from probābilis (“probable, credible”).

### Pronunciation

* (Received Pronunciation) IPA: /ˌpɹɒbəˈbɪlɪti/
* (General American) IPA: /ˌpɹɑbəˈbɪləti/, [ˌpɹɑbəˈbɪləɾi], /ˌpɹɑbəˈbɪlɪti/, [ˌpɹɑbəˈbɪlɪɾi]
** Audio (US):(file)
* Hyphenation: prob‧a‧bil‧i‧ty
* Rhymes: -ɪlɪti

### Noun

probability (countable and uncountable, plural probabilities)
* The state of being probable.
** 1610, William Camden, “Scoti”, in Philémon Holland, transl., Britain, or A Chorographicall Description of the Most Flourishing Kingdomes, England, Scotland, and Ireland, […], London: […] [Eliot’s Court Press for] Georgii Bishop & Ioannis Norton, →OCLC, page 119:For, a man may with as great probability derive the Scots pedigree from the Gods, as from Scota that ſuppoſed and counterfeit daughter of the Ægyptian King Pharao, wedded (forſooth) unto Gaithelus, the ſonne of Cecrops founder of Athens. But, as this conceit ariſing from the unskilfulneſſe of Antiquitie, is of the better ſort of ingenuous Scots rejected: […]
** 1682, John Dryden, Religio Laici: Or, A Layman’s Faith, London: H. Hills, published 1710, page 21:Thus, firſt Traditions were a proof alone; / Cou’d we be certain ſuch they were ſo known: / But ſince ſome Flaws in long deſcent may be, / They make not Truth but Probability.
** 1690, John Locke, “Of Probability”, in An Essay Concerning Humane Understanding, 3rd edition, London: Awnsham and John Churchil, published 1695, book IV, page 376:As Demonſtration is the ſhewing the agreement, or diſagreement of two Ideas, by the intervention of one or more Proofs, which have a conſtant, immutable, and viſible connexion one with another : ſo Probability is nothing but the appearance of ſuch an agreement, or diſagreement, by the intervention of Proofs, whoſe connexion is not conſtant and immutable, or at leaſt is not perceived to be ſo, but is, or appears for the moſt part to be ſo, and is enough to induce the Mind to judge the Propoſition to be true, or falſe, rather than the contrary.
** 1822, Paul Brown, “Of the Degrees of Faith, according to probability, and force of impression”, in A Disquisition on Faith, Washington, D.C.: […] [F]or the Author[, b]y Andrew Way, page 24:Thus though this degree of faith is but one remove from disbelief, (denial) nevertheless as much probability is given to one side of the question as the other, and we stand, as it were, on an average between two.
* An event that is likely to occur.
** 1625, Capt. John Smith, The Trve Travels, Adventvres and Observations, volume I, Richmond: William W. Gray, published 1819, book II, page 115:These waters wash from the rocks such glistering tinctures, that the ground in some places seemeth as guilded, that better iudgements then ours might haue been perswaded, they contained more then probabilities.
** 1837, L[etitia] E[lizabeth] L[andon], “An Old Man’s View of Life”, in Ethel Churchill: Or, The Two Brides. […], volume I, London: Henry Colburn, […], →OCLC, page 274:As all experience shows, the probabilities are, that you will waste the rich treasure of your affection on one who has none to give in return, or who is wholly unworthy of the gift.
* The relative likelihood of an event happening.
** 2006, Richard Dawkins, “Why there almost certainly is no God”, in The God Delusion‎, Boston: Houghton Mifflin, →ISBN, →LCCN, →OL, page 113:Hoyle said that the probability of life originating on Earth is no greater than the chance that a hurricane, sweeping through a scrapyard, would have the luck to assemble a Boeing 747.
* (mathematics) A number, between 0 and 1, expressing the precise likelihood of an event happening.
    The probability of an event A occurring is denoted P(A).

#### Synonyms

* likelihood
* likeliness
* probableness
* probality (obsolete)

#### Derived terms

* balance of probability
* conditional probability
* conditional probability distribution
* experimental probability
* frequency probability
* high probability trade
* in all probability
* in all probability
* joint probability
* posterior probability
* prior probability
* probability amplitude
* probability density
* probability density function
* probability distribution
* probability-generating function
* probability mass function
* probability measure
* probability paper
* probability process
* probability space
* probability theory
* propensity probability
* quasi-probability
* sequential probability ratio test
* theoretical probability

#### Related terms

* probable

#### Translations
### See also

* credence
* odds
* possibility
* verisimilitude

### Further reading

* “probability”, in OneLook Dictionary Search.
* “probability”, in Webster’s Revised Unabridged Dictionary, Springfield, Mass.: G. & C. Merriam, 1913, →OCLC.
* “probability”, in The Century Dictionary […], New York, N.Y.: The Century Co., 1911, →OCLC.